Mitsubishi Electric 800 Series Instruction Manual page 85

4
Control Method
V/F control (initial setting), Advanced magnetic flux vector control, Real sensorless vector control, and PM sensorless vector
control are available with this inverter.
 V/F control
The inverter controls the output frequency (F) and the output voltage (V) so that the ratio of frequency to voltage (V/F) is kept
constant when the frequency is changed.
 Advanced magnetic flux vector control
The inverter performs vector calculation and divide its output current into the excitation current and the torque current. The
inverter compensates the frequency and the voltage to output a current that meets the load torque to the motor, which improves
the motor torque at low speed. The output frequency is further compensated (slip compensation) to bring the actual motor
speed closer to the commanded speed. This control method is useful when the load fluctuates are severe.
NOTE
• Advanced magnetic flux vector control requires the following conditions.
If these conditions are not satisfied, select V/F control. Otherwise, malfunctions such as insufficient torque, uneven rotation
may occur.
• For the motor capacity, the rated motor current should be equal to or less than the rated inverter current. (Note that the motor
rated current should be 0.4 kW or higher (0.1 kW or higher for the 200 V class).)
If a motor with substantially low rated current compared with the inverter rated current is used, speed and torque accuracies
may deteriorate due to torque ripples, etc. Set the rated motor current to about 40% or higher of the inverter rated current.
• The motor described in the following table is used.
Mitsubishi Electric standard efficiency motor (SF-JR)
Mitsubishi Electric high-efficiency motor (SF-HR)
Mitsubishi Electric constant-torque motor (SF-JRCA 4P / SF-HRCA)
Mitsubishi Electric high-performance energy-saving motor (SF-PR)
Other motors (other manufactures' motors)
• Single-motor operation (one motor to one inverter) is performed.
• The wiring length from inverter to motor is 30 m or less. (When the wiring length exceeds 30 m, perform offline auto tuning with
the wiring in place.)
 Real sensorless vector control
• As the inverter estimates the motor speed and controls the output current more accurately, a high-level control of the speed
and the torque is enabled. Select Real sensorless vector control for a high-accuracy, fast-response control. The offline auto
tuning is required initially.
• This control method is useful for the following purposes:
- To minimize the speed fluctuation even at a severe load fluctuation
- To generate a low speed torque
- To prevent machine from damage due to a too large torque (To set the torque limit)
- To control the torque
84
4. Control Method
Motor Condition
Offline auto tuning is not required.
Offline auto tuning is required.